The subject invention relates to fungi resistant asphalt and to products including the fungi resistant asphalt when the fungi resistant asphalt is combined with a base sheet to form a fungi resistant sheet material. The fungi resistant sheet material of the subject invention is especially useful for roll goods and sheet materials that are used in roofing applications and residential and commercial construction applications.
Several fungi resistant asphalt containing products, such as roofing shingles, are commercially available where the products are made fungi resistant through the use of topping granules that contain or are coated with a metal or metal salt based on copper, zinc, or silver. However, to Applicant's knowledge, none of these products is made fungi resistant by adding an antimicrobial or biocide (a fungi growth-inhibiting agent) to the asphalt. While these granule topped products perform satisfactorily, it would be beneficial to have asphalt containing sheet products that are fungi growth resistant without the need to incorporate topping granules into the product provided these other asphalt containing sheet products could be economically and efficiently produced without adversely affecting the performance of such products. By way of example, the following are a few of the asphalt containing sheet material products in the building industry that are currently made with asphalt that is not fungi resistant and that have applications where it would be beneficial for the products to be fungi resistant.
Tarpaper is commonly used in the building industry as an underlayment in residential and commercial roofing applications and as a low cost but very effective housewrap under exterior siding, brick, or stucco. Typically, tarpaper is an organic paper-like felt that is coated and saturated with asphalt by spaying both major surfaces of the felt with asphalt or dip coating the felt with asphalt. Most felts used in tarpaper are formed primarily of cellulose fibers but some felts include mixtures of cellulose fibers and reinforcing fibers to make the felt stronger (examples of organic felts are disclosed in United States Patent Application Publication Pub. No: US 2003/0129899 published on Jul. 10, 2003). Other similar asphalt saturated sheet materials and most of the generic asphalt building papers often referred to as Grade D building paper could also benefit by being fungi resistant. Added fungi growth resistance should also be beneficial for other roofing materials made of asphalt coated nonwovens, such as but not limited to glass mats, polyester mats, and polyester spunbonds. Single-side asphalt coated sheet materials where the base sheet, by itself, is naturally fungi resistant, but the asphalt coated sheet material is not, should also benefit if made with fungi resistant asphalt. For example, a single-side coated polyester that was fungi resistant could be used as a high quality/high strength roofing underlayment for clay and concrete tiles, as a canal liner, as a low-cost housewrap, as a packaging material for lumber, and for other uses. Similar breathable, hot melt coated, nonwoven sheet materials that could benefit by being fungi resistant are disclosed in United States Patent Application Publication Pub. No: US 2004/0023588 published Feb. 5, 2004. For certain applications, it should also be beneficial to have asphalt saturated fiberboard that is fungi resistant.